The invention relates to a method for impelling water in a water area.
A water area e.g. a lake or a bay is not an isolated eco-system but is on the contrary very dependent on the conditions in the atmosphere and in the surrounding area from where the water area receives water.
With the precipitation, the water is thus added sulphuric acid, H2SO4 and nitric acid, HNO3, which especially in lime-deficient water areas produce an environment in which plants and animals have difficult living. Furthermore, the degrading ability of the bacteria is reduced so that the amount of non-degraded organic substances in the form of humus compounds is increased.
The water flowing to the water area from the surrounding area often brings together with any discharges of waste water from urban areas large amounts of a number of nutrients in the form of e.g. nitrite and nitrate along with it whereby the biological activity of especially algae is increased substantially. Thereby, the visibility depth in the lake is reduced, and bottom plants begin to die out.
Concurrently with the death of the plant biomass in the bottom layers, the oxygen supply of the water area is reduced resulting in dead organic material not putrefying fully, and a layer of unputrefied organic material therefore settling on the bottom of the water area. The environment especially at the bottom of a water area can sometimes be so heavy strained that higher organisms no longer can survive. The water area is said to be xe2x80x9cdeadxe2x80x9d.
The living conditions at the surface and bottom of especially a rather deep water area with a thermocline between a top, warm zone and a bottom, cold zone can however be very different. Thus, oxygen will frequently be plentiful at the surface even though the water at greater depths will be low in oxygen. This phenomenon occurs especially in periods of formation of thermoclines where there is not sufficient wind to effectively set the water in motion.
With a view to set this problem right, attempts have been made to impel such water areas artificially by means of mechanical pumps driven by electric current or by internal combustion engines. However, the employment of this kind of energy to treat often very large volumes of water is disproportionately expensive and to this should be added that the employed equipment which in any case are operating with movable machine parts is liable to operational failure and therefore require inspection and maintenance often under difficult conditions at sea. The method has therefore not spread appreciably.
The object of the invention is to provide a method and a pump of the kind mentioned in the opening paragraph, which is simple and reliable, and which is arranged to impel water without costs for external energy.
A second object of the invention is to employ the impelling process to remove predetermined constituents from the water.
A third object of the invention is to employ the impelling process to add desired additives to the water.
This is achieved by means of the novel and unique features according to the invention whereby waves in the surface region of the water area are transformed to whirling water in the form of two swirls which is led down towards the bottom of the water area.
The whirling water advantageously serves for enriching underlying regions which are low in oxygen with oxygen from the surface water which is high in oxygen and atmospheric air which the waves have brought along with them. As the whirling water has a considerably higher velocity and a correspondingly larger energy content than a corresponding non-whirling water flow, the surface water is mixed with the bottom water especially efficiently.
The invention also relates to a pump for performing the above method. The pump comprises at least one horizontally extending whirl pipe submerged in the water area and having a longitudinal slot, and at least one preferably curvedly extending baffle which has a top front edge facing a wave front which might occur in the surface region of the water area, and a bottom rear edge extending along the slot. Water which in the form of waves flows in towards the at least one baffle is led via the longitudinal slot tangentially into the whirl pipe whereby the water is set in heavy rotation in a way known per se so that the water will form a whirl in the whirl pipe.
The novel and unique features according to the invention is that the ends of the whirl pipe each is fluid-connected to a submersible pipe extending towards the bottom of the water area. The submersible pipe serves for conducting the whirl in the whirl pipe down to the region which is desired to be mixed with surface water high in oxygen and atmospheric air.
The pump according to the invention has a simple construction and functions without movable parts. It is therefore reliable and for long periods of time does not require inspection and maintenance. The impelling process passes off without use of external energy and consequently heavy running costs. Only the present kinetic and potential energy available in the waves is used for the impelling process.
A flowing whirl has the peculiar characteristic that it relatively easy can change direction without significant to loose energy or to change structure. This advantage is best maintained when the whirl pipe and the submersible pipe are interconnected by a bending allowing the whirl to change direction without thereby causing turbulence in the rotating water.
Under the bottom mouth of the submersible pipe, a barrier can advantageously be placed in the form of bowl with a wall which, seen in cross section, curvedly passes into an upwardly directed central point. The bowl reverses the out flowing water of the whirl so that the water flows upwards in stead of down into the bottom where it could cause damage by unwantingly whirling the bottom material up and thereby pollute the water.
A water area can have a considerable horizontal extend. In order to get the bottom water in areas at a large horizontal distance from the pump mixed with surface water high in oxygen, the bottom part of the submersible pipe can be bent in relation to the plumb line. Thereby, the whirl is given a velocity component which causes the whirl to begin travelling towards the mentioned areas.
When there are two whirls with opposite directions of rotation and when the bottom parts of these whirls both rotate in the same direction as the water is moving on opposite sides of the whirls, the whirls will repel each other so that the water across a very large bottom area is enriched with oxygen.
The rotation of the water in the submersible pipe causes heavy constituents to be flung out towards the wall of the pipe while light constituents will move in towards the centre of the pipe. By at a wanted level connecting the submersible pipe to a removal pipe led into a specific layer in the whirl, this layer can be completely or partly removed from the down flowing surface water.
An unwanted biomass can thus be separated and via the removal pipe led to the surface where the water is strain off. Alternatively, the removal pipe can be connected to a filter bag placed in the water.
With several removal pipes led into each their layer in the whirl different constituents can selectively be removed from the water.
In an advantageous embodiment the whirl pipe can furthermore be fluid-connected to an intake pipe which is open at the top. When the intake pipe ends above the water surface, extra air in sucked into the whirl pipe due to the negative pressure in this pipe. Thereby, the whirl will directly draw atmospheric air down with it to enrich underlying water regions with oxygen.
The intake pipe can also be used for pouring additives down into the whirl pipe. For example lime which is used to change the pH value in e.g. acid lakes is then taken with the whirl down into the lake where the lime is effectively mixed with the acid water.
When the intake pipe ends below the water surface, the surface water is sucked into the whirl pipe which thereby via the submersible pipe sends extra large quantities of water high in oxygen down towards the bottom of the water area.